Method of leaching sulphide and mixed ores



m, w25. v

' 251, D. VAN ARSDALE METHOD OF LEACHING SULPHIDE AND MIXED @RES FedMay 1SD 1923 LQQDU @QOSU v For this reason, a method involving` only wei and eleclrolytic siens, and eapahle of obtaining` values lroni hoih the oxid and the sulphide eonr poundn hy one course of' ofLieralLionS, deeidedly pre lierahly, in many eases, as eoinpared with separare methods for eaeh elass ol eoinponruls7 even at an equal eoSt, l is an iinporinn ohjeel; of my invention 'to provide a eennnereially praetieahle Single en? traction treatrnenrflor mixed ores of the character referred to,

AS a eonerele exainpleoof the application of my dirieoveries in a process of treating inixed copper' ore?. l may refer ro lhe trenb men-'c ol a hody of dry-erushed ore adapted ro pass hroug'h a l/L ineh inesh or lese. ln ihiay eonneerion` .l ma)y sliaie that anitalile erunhi is highly7 iniporrani.. lo he heet snc of iny {.roeeaea and may eontrihne noi, only 'Lo a completen s of recovery lint to ohriare he neeerfi'l'y for he application of heal', during leaching; and lio ehorle l'he period ihereef. .arent in 'exhieh eoinpleeness of r errishiinjg :nf 'l he inferred `from lihe reef, hab an ore eru;-;hed lo page a lli inch ineeh ,has heen l'onnd 5to y eld., under rho treatment hereinafter deserihed5 railings eoniaining ahoul .5% eopper7 whereas the saine ore when ernshed lo pans a l@ ineh niesh has yielded4a nnder idenli al treatment, railing?, eentainine; ahou .31% copper, and when rrnshed io pass a l5 ineh ineffh only Copper, or lessi, in ihe tailings. 'ln sionie eases:i even ihrer ernhingg; may he enro ij'ld izo ai 'vantage lo peri'nil access of solnrio'na lo the eoi'iper minerals,

' i iadly, lhe proc o wnieh l snlijeeb sueeeesi've hor." s ol yeuished oi in- `rolvei'l a pereola'iion method of exlrarliion 54o eori-'elaH-d with a method of eleelrodeposition rh ie eleerirodeposition yields, as an ineidenral prrnlnct, reid solnl-ion of a rrie, Sulphate hie for use, with or without the ndii 'm of acid7 in the e);- rariioii oir3 a lnipher quantity of f 'rnnhed ore` in v prorewi heine in rhin Senne cyclicals el this procedure dependingg; in parl', npr i the prarriral lin'ii'l of tolerance of un iron .inlplinle privent during` eleelrolynin and dnriiie,- exizraeiion.

iii'iil'hour :hairline-5 l' prefer to'treal; aihody oi" finitahly ernsned ore to an extraction in "n :nineom fiolvent eonalning. in, addition ahon 3% Snlphnric aridt 'fp or more o? lhe "i oi" herrie sulphate, :indeo 'i 1 of ropper nulphn're, ivhi.' e present in any eoi'irenirfnt or per-seid@` Say, 'from 2.5% ro ill he nndi rood ha'r llhe 03nd niereiallv prneieahle.

des i rs i'n'lueneed hy linenens olaction ol ,ferrie salts under eerain eondi tions. The following` equation is an exaniple of such action:

'ius-w02(sonenflammerfr s.

t has also heen hnovvn that the Solution produced hy the ahove equation may he trea'edhy electrolysis Se as to regenerate the Solvei'it. Other inelzhods of regenerating ferrie iron has heen proposed, hul` have here tol'ore not proven rn'zuftieahle.

There have, however, heen ohslzaeles, aside from 'ehe ahove mentioned necessity 'l'or line ernnhingg in the way' oi" a gn'aclirel, applicam tion of he ahove simple method ol leaehing Sulphur roniponnds of copper with ferrie iron and snhseqnently regeneridine; hy eleelrolyeier Up to #he presione time7 eleelzroly o? copper .fnlphaie solntionn carrying iron has not l een round practicable when no inueh iron is: present that the Strength o'l" Ferrie iron` incidentally produced during eleerrolysie rin. s ilo a fignreln lhe neighborhood of .3% to .5%3 sajv :ihoir .ill/7,70.

vln Yfurther explanalion. ily niay he stated tha solulons carrying; onlyy .3% ro .5% 'ferrie iron are naeive on ysoine sulphide eonij'ionnds ol' copper; and, on others7 ehe action is slow and may even require heating'. l'ith solutions eon'raining' larger amounts ol ferrie roxn say Jfrom .5% o 1% or morenl l have discovered 'that the solvent action is inueh more aeli\'eand rapid, and on seine ores: ehe neeeeisi'ey for warming; the `-olution$ is thus ohvinled,---with substantial advan-- ragena from the siandpoint or eeononiy. "il, will he undersl'ood from the foregoing;l dial'. in the employment of Jerrie sulphate leaehing s-oliitionn, Sinai-ting vriiln Say 1% Vi'errio iron, eoinplee redire-ion or ferrie iron hefore eleeifrolysis eannot he had eoonon'iieally Afrom the slandpoint of leaching ellieienoyM although his Complete reduction has hereto'l'ore heen regarded as essential to goed eleetrolytio practice. i

I have discovered that hy modifying elertrolytie eondition, eleetrolysin can he enried ein wir-h .emnnierrial yieldn` of :ol'ipeig in the presence of very nineh higher aniounls of ferrie 'iron han have heretofore heen Adrought permissible, and even in the presence or' an amount lQnllieiently high to give a highly aefive Solvent pereentae'e olf ferrie iron. L therefore, prel'er to utilize eonjoinrly my respective discoveries thai; mieli solutions arel highly :relire solvents, and that it is 'naetieahle to nia-die rhein hy lll) electrolysis; sind., to do this, l prefer to leach the ore in such manner es not to obtain e complete reduction of the ferrie iron present, aiming rather to so proportion ore and solvent that n. `goed extraction shell 'ruhe place while the per cent of ferrie iron presi ent is still high enough to uct Avigorously. 'lhis point will, olf course, vary' with dilier ent ores und conditions; hut, iu general, I have Viouiulil' not necessary' to reduce 'ferrie iron hclou' uliout 2%, und7 iii sonic ceses7 not below .5%. Generally speaking, on most ores, u uiuxinuini strength of 1% of lfcrric iron is suiiicicnt; but higher percenlmges muy he used, il necessary. ji4 preferred method hy which high percentages of ferrie iron nuiy he inode, hy electrolysis is referred to subsequently heroin.

"When priu'ticuhle, l prefer, us indicated, lio trent ores by percolation; hut it is not essential to the` carrying oui; ol' my process, Agitntiou of crushed ore suspended in the solutions, followed by continuous countercurrent deczintution und wushii'ig` in ight oli-- viously he used; und this procedure would he entirely appropriate to, for exemple, the recorery of values 'from tailings after a conn ccntrution treutrnent of ores.

The duration of the percolation treatment ot a given body of mixed ore 'will vury with the character et the orc eind muy he irom four 'to twelve doy/fs. The. use of the described routinely high content of ferrie iron in the leach liquor inches possible the shortening or time of treatment und increased eX- traction even Without the, ipplicution o'l heet. Sonie application heat during' the iinul portion of the period oit c itreciion niej", however, he ecoi'ioiniciilly justiiied fior sonic orcs.y As is nou7 customary in operations ol this character, the couniercurrent principle is preferably cn'iployed throughout the leech` ine: und, whenever Asuch :i course shell he indicated hy a'. coinpurison of the copper content of the ore `with the titre of the re generated solvent resulting; :from electrolysis, ns hereinafter described',suitable uddiiions oi acid may he inside to the .leach iii uor: hut otlerwise it islet im iortzince that' 'A portions of wash or leech liquor he so controlled is not nuiteriulllv to change the total rolun'ie ot solution, This een he done foy well known inet-lr ods, provided there is no excess or deficiency of solution constituents. lirith a building up of any metal, e. g., iron, in solution, u proportional discard *lor special treatment is required, or other method, e. g., the one hereafter described may he used." When the. application thereof to successive portions of vore undergoingextraction shrill have produced e liquor sufficiently rich in copper 'contentandtuilings which Acannot profitably be further treated, the' lottery-solou ereted by filtration or otherwise, muy he diem is often 'u nuuter ot great practical impor tence, both. with respect 'to the tol'ul enjiount present und with respect to the buhince'of ferr-ruis und 'i'erric iron in succeeding cycles; und while my pi'eierred method of conti'olf lingl the iron content .ii'ivolves features of CTI novelty which ure separately claimed in copending application (Sero No. 539,970 tiled .l'lirv 1S, 1923). I outline herein. one of these methods inerel-y for j'iurposos o'il complete ness, und in order that the cyclical charac ter and practical advantages of the, method herein described und claimed muy' be heiter understood. In this connection, as stated, :in excess ot the total .iron muy he compensated by u solution discord. A neutralizing accompanied by uil'ieuting hns also hereto-- fore been used to eliminato iron troni liquors ohlziiined by the leaching ot iuixed orcs of copper; huttlie neutralization referred to involves :icid loss and is expensive. l here l'o'iuid, when the accumulation of iron .in u leach liquor cyclicully used is comparatively rapid, such iron muy., it desired, he eliminated hy a'precipitationeliected vviihout neutrulizuiion.7 hy u incre application o'ifsuitihle pressure to the liquors while the suine are heated; und this may advantageously he, done hclore the leach liquors ure subjected to electrolysis, any suitable upparutusihciug employed. in addition `to cases requiring these expcdients, which are for the purpose of rontrollinzgr excess ol totuliron. there um): arise cases in which the 'ferrous und ferrie iron muy not hulunce :is required in successive cycles, and in order to ineet, for example, the case in which the reducing power 'of the orc is such would othervvise4 result in un occuimdution o'ijl'erric iron, l muy use in conjunction, during roy electrolysis, u suitable proportion of unodes7 such emphw ite auodes7 which ure relatively eilicieut in the regeneration of ferrie sulphide Yfrom 'llerrous sulphate, together with u suitable proportion of other unodes haring :i lower eiliciency -in this ldireetiorisuch as :modes oi' leiuL-the ratio of; these two types of u nodes being so adj usted as to keep the ferrie iron in balance during successive cycles. o

As indicated above, o very import-:uit practical feature of iny invention is the method of electrolysis hy which inlay produce \ora regenerate larger amounts oi -ferric iron than have hitherto heen thought possible et any reasonable cathode eliiciency.

'The presence or ferrie iron durihg; electrol-k fio' l .lil

highly objectionable, and objectionable in proportion -to the amount of ferrie iron present. 'l`his view has apparently been due to'an appreciatc `n ot the vtact that `l'erric iron is an eliicient solvent for metallic copper; and unless means are taken to counteract. the mentioned tendency to solution, the cathode eiliciencyk is correspondingly reduced. Statements are found in thcliteraturc to the etlect that at about .5% ot' ferrie iron., deposition elliciency becomes very low; and, as a practical proposition, at one large installation using` electrolysis, maximum Ferrie iron is held near .4%. Contrary to the prevalent opinion, l have, however,

iound that'commercial yiel'ls of copper per kilowatt hour n'iay be had with solutions bcginning' at about a zero content of Yferric iron and ending at. about 1%, or even jmore. rlhat is to say, within the mentioned limits, the actual percentage olt lerric iron may be disregarded, -althougln obviously. the overall elliciency 'l'or a given amount ol copper "deposit, will vary with the point. at which 'torrie iron starts in beginning electrolysis. in order, therefore, to maintain any eonstant deposition efficiency, the amount ot' copper deposited must vary inversely with the average percentage ot ferrie iron bellore and after electrolysis.

In operating with a higher average ot ferrie iron, therefor, the solutions have to he returned more frequently in ordcr to leach the copper 'from any given quantity et ore. This is don/e at an expense of pumping cost, but it may nevertheless be entirely `iustitied in View of the fact that, as stated, high torrie, iron is very desirable from the standpoint of? leaching eiiieiency.

lnorder to obtain commercial cathode efficiency during electrodeposition of copper, l have found it advantageous to employ a current density ot at least seven to eight amperes per square r'oot, and the current density may be raised to fifteen amperes or more per square foot; and I have found that, by suitably proportiomng current density to `Ferrie iron, the latter may be disregarded. 'ilo obtain commercially profitable yields, as measured in terms of pounds of copper per kilowatt hour, it is also important that low voltages be employed; and such voltages may be obtained bv a moderate heating (say, to 110' degrees F.) in connection with which it may be advantageous to employ known means for depolarization, and also to employ. as large a proportion ot graphite anodes as may be.

consistent with the considerations indicated above. l

The preceding si'ieeilieaiions contain a full discussimi olf the ineihods by which this inventionv may he applied under various eonditions. in order that the process may be apracticable fic example of its application. I do not claim the discovery of the solvent action of 'ferrie iron, but only new methods of making and controlling the reagent so that itScuSe is rendered practicable, which has not been' the case before. An important Arizona copper deposit has large tonnages of ore carrying about 1.25% total copper, of which so large an amount is in the form of oxide or silicate that the usual methods of concen'- tration do not give high enough recoveries.

ysis'of copper solutions has beeuconsidered clearly understood the following is a speci- I A combination method of leaching andi Ilotation is'possible but may not be commercial Vfor the portions of the` ore` with too low a proportion of oxide or sulphide. On

this ore the method oit' direct leaching as4 vdescribed has resulted in perfectly satisfactory extractions. For example, the treatment of a large amount averaging 1.40% total copper, .69% oxideeopper, and .71% sulphide copper has given tailings containing 199%, .01276, and .187% total oxide and sulphide copper respectivel The steps by which this resu t were ob-. tained were as follows: dry crushing to pass a three mesh screen, loading the crushed ore into rectangular leaching tanks, subjecting it therein to contact`with leaching solution ior71/ to 10 days, drawing off the main leaching solution and subjecting it Ito electrolysis after addition of acid, Washing the. ore by successive unit' volume Washes of which the strongest is added to the main solution and the others successively advanced for the next cycle, finally Washinthe ore exhaustively with a circulating Was as described in a separate applicationi (Serial No. 665,463, filed Se tember 28, 1923) and discharging the was red tailings, the operation being then repeated on. a fresh charge of ore.A The mechanical operationsthe ore and to electrolysis averaged Cu 3.1%,

'free .H2SO4 5.27%, total -iron 2.28%, ferrous iron 1.43%, and ferrciiron 0.85%.V It should be noted that the last percentage of ferrie iron is -still at a point at Whichlit is an active solvent. and. is considerably above the percentage higherto thought possible as solution Yfor During the same period, the tank house was operated at a current density averaging 15.28 ampere's'per square foot, .with a cathode eiieiency et 65.11%, an anode elle cieney of 55.2%a1u1 ayield et .715 pounds copper per lulowatthour. The reducing electrolysis.

wliee the electi'ol :weemoclimeeizer ol the ore in this pofrticuler cese was suoli iliot e balance o ferrie iron could be maintained willi ell le cl onocles. y,

The single figine of libe drawing is a 'ilow sheet illuslre'lino ille present process. vllie oie is teken lii'sll-io libe Coarse crushing plant il.. thence to stm-'ege bins ll, u line crushing and Sei'eenii'ig olan. C and s sampling piani; D; whence it passes so the leaching tanks At any stage oli Jshe operation there are ,live of these used in sei-iesytbe solueion pass ing; lluoupjli one tbe other of the se'ii'ies. These numbered l, 2, l, 5', in Whieli "iie leaching opeietion .is being pelf'oimed et the period illusteee; number o, Wliieli is being" loaded snail numbers l und 8 which :we used` in elle Washing opereion. The copper soiuzion from Jalie series i eo 5 flows by 'wey oi Une -ine ll' to 'the coppe? solution soiegge benk (l, lience by olie line il', along Wliicli it is ieinoieed by eeicl along tl'ie line il, anni inolly to the tank house K Lie pioeess is carried out. is teken ell by the line The collode ooppei' L. 'liie eeiii solution is token oli" from lie tank house izlnougli *olie line lvl and abe oeicl solusion storage tank N whence it passes by the line to the leaching tanks ln my comending application Serial No. 365,43. filed Sepeuibei 28. i923, l lieve deseribe e method, Washing the iesiflue of the ore el? lesoli'ng, and liis is illusrsiecl in bentbee,l.lio1'igli noz"J `clziimed in lie piesens o'pplieazion. il series foi' moles 'loir storing the eclyeneinfg wesh Weeif is illus'rei'ef" oi'. i nuiiuliereci l., Q'. 3, e, 5, 6 .ecspeeh The leaching' seul/a 'Z' carries ille nlue which being' subjeoecl 'bo tbe u opei'azion. The iesli Wetereners lise mult lie line {.3. After pessn'xg 'rbrounli lille moieiiol the Wafer posses by lines Il to and from wesh sboioge ianlf; l'lioneo buck to lille '-inl 7, through the ino.- 'eiial lieiein and Lo und oin wesh stoffau-e teni; enfl so on through tbe several mieli s'oroge tanks. The lest and stione-- est mieli Wale? lien posses by lie line S into llie line ll ceri-ying alle cooper solution from ille enlis which ere employed llie lcriciiing. The Washed 'i'iesiflue is eeiiieil oilJ by 'lie'liue T. li, will be u nclcstood lmli die eiglu'; lezieliing tanks shown ein usefl in sooo. sion. For exemple. ni'er.' working es described for o eei'uin period of Lime., *elio eomieeions will be oliei'iegecl so .fis io use numbers Q. 3. 4.-, and (S es the series of loeeiiii'ig benlisg i'iumbei-4 es "the "rook which i'eeeiw'es ibo fresh oie enel number 8 mi; *alle onl; inwliioli libe Wasliingg' takes pl .ii'fing in Clie some wey to use all 'lie lenlf* leaching in succession for leerling.

' "noel of li-iiiinention is applicable 'i no uniege not on y but. also conoeniiees, amd the leien oies" :is used that various features 'io 1% or more therein 'will be unei'sood es including eoncentrales.

(ll: Will be understood by those skilled in of lie process herein described :may be independently used, and; that various moclilieotions of my preferred processjwill be found possible Wieliou; depeirture from the spirit and. scope of' my invention as the seme is indicated above :incl in the following eleims.

' llfllat l claim is: f l. A method of tref-itingniiiied ores of copper, which comprises vdry#eiusliing unijoasied mixed ores to mil; access of solu'iions to the Coppel' min erols and lereeftei subjecting the seme to o. leaching with en ooid solution eonioining about .4% to 1% or more of ferrie iron.

2. A method ol? treating miieecl. ores of copper, which comprises drycrusl1ing zin-- roasted .inixefloies "so a suitable fineness end thereafter subjecting the seme `to s. leaching; with an acid solution containing about .4% to l or more ol* ferrie iron, the seid soluion being lirst eniployeol eolcl.

method of meeting .mixed ores of? copper, which comprises roasted mixed ores toe suitable finenese and thereafter subjecting the seine to e leaching Willi en acid solution containing about .4% to 1% o1: more oli :ferrie iron, tbe resulting iicli liquor being lle-reellen subjeeecl to en electrolysis odepted to 'the deposition of e. size sullicien to pei-`l eoppei und the siinulseneous regeneration.

oi e leach liquor oi. subseniiolly the chaieciei previously employed. l

il. inezliod oi' 'treating mixeel otros of copper., which eompivises diy--ciushing unroasted mixed. oree to e suitable fineness :incl thereafter subjecting tbe seine to eecliing with on eoiol solution conizoining about .4% of leirio iron, the resulting rieb liquor beingthereeltei subjected to en electrolysis adapted to zlie denositiui of copper and. the simultaneous regenel'etion oi' e leech liquor ofi,s substantially the elimM outer previously employed, lie. anioun of ferrie ixon being controlled by the employm nient, (lui'ing electrolysis, of :i suitable piopoi''ion of eleetrocles egieieney in the regeneration of ferrie iiron.

5. A, method of meeting mined ores of copper, which ooniiprses dry-ci11sl iing such ores to :i suitable size, tlieieafei' subjecting' the crushed piocluet to s. leaching by ineens of on oeicl solution conaining about .4% to 1% oi more of fem-ic iron, lie soliuon being; et i's; employed cold und subsequenly heeled. only satisfactory extraction moy require.

55. method of treating' mixed ores of copper, which eoi'npiises dry-Crushing; suoli. ores lo o suitable elioieziiier subjecing crushed product. to o leaching' by means oi en eciil solution eonteiniu'v ferrie iron9 of high enel of'lowvl the solution being at first' employed cold and sul'iseqncntly heated only as satisfactory ex traction may require7 subjectingthe resultant rich liquor to electrolysis, andy so controllingthe content of iron as to restrict the percentage of ferriel iron in the regenerated liquor to a quantity suitable for use in subsequent extraction..

7. In a cyclical process tor the recover-37 of values from material containing sulphides of copper, thc step which consists in leaching such materials with a solution containing a determined percentage ot ferrie sulphate sntlicient to assure a high etiiciency of extract-ion and without permitting` the content of ferrie iron in the leach liquor to tall below a` ligure. suital'ile. to such extractioil, no eti'ort being `made to avoid the presence ot ferrie iron in the resulting rich liquor.

8. ln a cyclical process for the recovery of values from material containing .sulphides ot' copper7 the step which consists in `leachingy such material with a solution containing' suilicient terric sulphate to assure a high etiicicncy ot extraction, and without pern'iitting the terric iron content oit the. leach liquor to tall oelow about'l .4% to 1%.

9.,:tn a cyclical process for the recovery ot values troni material containing sulphides ot copper, the step which consists in leaching` such material with a solution containii'ig sutlicicnt ferrie sulphate to assure'a high ctiicicncy ol extraction` and without permittingY the ferrie iron content ot' the leach liquor to i'all below a ligurey suitable to such etlicient extraction, and thereafter plating,l out copper while tolcratingi4 the presence ot tici-ric, iron in percentages suitable to the, mentioned high eiliciency during the subsequent reuse o the regenerzited leach liquor.

1t). ln a cyclical process for thc recovery ot' valuesl troni nuitcrial containing sul* phidcsotl copper7 the step which consist: in plating out copper by electrolysis while toleratin;r the presence ot' 'terri'.l iron in percentages suitable to a high ctlicicncy in the subsctpicnty use ot' thc regenerated clcctrolytc as a leach liquor.

ll. ln a cyclical process t'or thc recm'crvol' values troni material containineV sulphidcsot' copper. thc step which consistrl in platingr out copper by electrolysis while tolcratinc' thc presence of vtcrric iron in per-- ceutapcs up to about lj. or more.

l2. ln a cycli Ial process Jlor the recovery of values from material containiir;h sulphid'cs o't' copper. the .steps which consist in leaching' `such materials with an acid leach liquor containing; tcrric iron and without iir-crinittint' the content ot tcrric iron thcrcin to l'all below a tirurc suitable to etlicicnt extraction and thcrcat'ter platine' ont copper while tolcratingf terri" 'ron in percentages suitable to subsequent ctlicicnt extraction.

said extractions being conducted on the conntercurrcnt principle. c

lil. n a cyclical process for the recovery of values from material containing sul phides ot' copper. the steps which consist in leaching such materials with an acid leach liquor containing ferrie iron and without permitting the content` of fcrric iron therein to fall below a {igure suitable to etlicie'nt extraction and thereafter plating` out copper while'tolerating 'licrric iron in percentages suitable, to subsequent etlicient extraction, said extractions being condu `ted on the countercurrent principle and with any requisite addition of acid.

14. In the recoveryI of copper from matcrials containingv the saine in sulphide forni by a cyclical process involving an extraction which tends to convert Aferrie iron into tcrrous iron and an electrodeposition which tends to convert Ylcrrons iron to ferrie iron, the method which consists in maintaining` the i'crric content throughout at a level dctcrinincd by the elliciency o'l' extraction.

l5. ln thc recovery ot copper itroni niatcrials containing the saine in sulphide Ytorni by a cylical process involving.1 an extraction which tends to convert ferrie iron into terroirs iron and an electrodeposition which -tends to convert ferrous iron to ter-A ric iron, thc method which consists in maintaining the it'crric content. throughout at a level determined by the ctticiency of extraction, up to lC-t or more of 'terric iron being tolerated duriner the elcctrodeposition.

ot copper.

iti. ln the recovery of copper from materials containingI the same. in sulphide torni hy a cyclical process involvingl an cxtraction which tends to convert 'ferrie iron into "ferrous iron and an elcctrodcposition which tends to convert ferrous iron to ferric. iron. the method which consists in maintaining the l'crric content throughout at: a level determined by the efficiency ot'v extraeA tion. up to lf2' or more of 'ferrie iron beiner tolerated during they electrotlcposition ot coppen said electrmlcposition being conducted at. an elevated temperature.

iT. ln the recovery ot copper from niaterials containing the .saine in .sulphide torni luy a cyclical process involving' an extraction which tends to convert ferrie iron into 'ferrous iron and an electrodeposition which tends` to convert. ferrous iron to terric iron. the method which consists in maintain inf: the lerricy content tlnougfhout at a level determined by 'thc ctlicicncy ot extraction. up to 1% or more of ferrie viron heiner tolerated during the clectrtulcp isition ot copper. said electrodcposition being eonducted with a high current density.

'18. ln the recovery ot copper troni ma tcrials containingY the saine .in sulphide form by a cyclical process involving en ex loo imo ferions iron and an oeo'o@position 'whoh jo convert fm1-ous iro-n to fer- `tion, up bo 1% or mofal of ferrie iron bo ing tolemo during the olooizrodopostoo of coppe?, smid oloo'odoposiion 'boing oon` oo with the of @whim modos. A n

191 'lin tho rooovoy of Coppe? from ma# tenais containing tho some in sulphide foon by o oyoool process involving an e1;- mcon Whoh iono to oonverrtferr-ic iron .loto @Pouvons 'on and n n oeotrodepooton W" @ends o ofym'o; oxlous iron o ferrie t"om ho n1et1owhioh Consists in zrooif im .Qing 111e, ferrie oontom'; boughout at zu leve?. detomuinod by the ooioncy o extmction, up to 1% or more 'of 'fonia iron ingr "oorote'd ming tho oectrodoposon ofooppel, sair eootl'odepooiwion boing con duomo undo? oom'ons of current density pxosen; to bo disregarded.

Q0. i119, ooovory of copper from miv terlos containing the oil-me in sulphe fo by o ofoloo proooss Whloh tonos to by oyooo process which condo to convert oo A iron' more of fem-.io iron to obtain noppes." inherethe quantity tolora'bo 'during containing ofal i'ooony in quantities suitablo, upon Conversion into o em'o o'rmyfor a Hmxmlm leaching offoizi(moy7 and not in. exceso of hoquanuty tok-roble during dem -tlvoysis, said extraction being begun whout oppcoton of heat.

A oyccn process oi mating mizie oros of copper, which comprises treating the with' on acid solution of o'o iron use of a largo perootago fom olons-jy' o?? zon or moro ampores boing moA therefrom :md-fo simultaneously regenerate :1 leachliLuor offsuhstautiully the character previously employed.

' 30. Tho method of treating ores of cop- 5 per which consists iu subjecting the Same to a leaching operation with :m acid S0h1- tion ,'outniuiug n determined substantial percentage. of ferrie iron und subjecting the resulting rirh liquor to4 electrolysis to Lleposit the mpper therefron. 11ml to regeu- W @rate a leaclrliquor containing` the Suid-(letermined percentage ol" terrieirou.

In testimony whereof have siguerl my mule to this specification.

GEORGE I). VAN ARSDALE. 

